Loud-speaker



Oct. 2l, 1941.

J. MCW. STONE EVAL LOUD-SPEAKER Filed Feb. 28, 193:3

Patented Oct. 21, 1941 LOUD-SPEAKER v.lohn McWilliams Stone, St. Charles Township,

Kane County,

and Carleton YT. Weibler, St.

Charles, lll., assignors to Operadio Manufacturing Company, St. Charles, Ill., a corporation v of Illinois Application February 28, 1938,v Serial No. 193,054

1 Claim. j(C1. 179-1155) y The invention relates to loud speakers ofthe electro-dynamic type and has for its primary object the provision of loud speaker construction, of the kind described, which is exceedingly simple in construction and maybe quickly assembled.

In a preferredform of the invention, the improved loud speaker comprises a sheet metal housing preferably formed in one piece, which housing comprises a pot cover and a basket member, the pot cover serving as .a housing for an electro-magnet and vforming also part of the magnetic circuit. In this form of the invention, a part of the pot cover is the sole path of part of the magnetic circuit of the electro-magnet. The basket member is of conventional form and has a frustro-conical diaphragm mounted on it.

Other objects and advantages will become apparent as the following detailed description progresses, reference being had to the accompanying drawing, wherein- Fig. l is a rear elevation of a loud speaker which embodies the invention.

Fig. 2 is a section taken on line 2-2 of Fig. 1, and v Fig. 3 is an enlarged fragmentary section taken on the same line as Fig. 2.

Referring to the drawing wherein a loud speaker embodying a preferred form of the invention is shown,fthe reference character I designates generally a housing member which is formed preferably from one piece of sheet metal. The housing I0 is formed from a magnetic metal as will be readily understood by those skilled in the art. The housing II) comprises a pot cover II having a cylindrical wall I2 and an end Wall I3, the end wall I3 being apertured as at I4 to receive one' end of a central pole-piece I5. The cylindrical wall I2 is preferably of somewhat enlarged diameter at its open end to provide an annular shoulder I1 within the pot member II. At its open end, the cylindrical lwall I2 terminates in an outwardly extending annular ange I8 which has formed integral with it a frustro-conical wall I9 which terminates in an annular flange 20 to which the outer periphery of a frustro-conical diaphragm 22 is secured by means comprising a felt ring 23 and a plurality of grommets 24. It will be noted that the annular flange 20 has an integral flange 25 projecting forwardly at its periphery, which flange 25 is adapted to center the diaphragm 22 with respect to the frustro-conical wall I9. The frustro-conical wall I9 and the annular flange 20 form a part which is generally called the basket. In this instance,

it is designated generally by the reference charac ter 26;.v f

l p Secured by adhesive, or any other suitable fastening means, to the annular flange I8 is a disc 2,1 of flexible material; the disc 21 being provided with a plurality of Vannular corrugations 28 which increase the flexibility of the disc. The disc 21 has a central aperture 30 and the forward end of a tube 3I is secured in the aperture by adhesive. The tube 3| carries the voice coil 33 which is disposed in the aperture 34 formed in a disc 35 of magnetic metal, the disc 35 being sometimes referred to in the art as the outer polepiece. It will be noted that the outer pole-piece 35 rests against the annular shoulder I1. In the preferred construction, the outer pole-piece has a press t with the inner surface of the pot cover.

The pole-piece I5 is cylindrical in form and has its end I5a projecting through the aperture I4 and through an aperture 31 of a disc 38 preferably formed of magnetic material. An annular shoulder 39 formed on the pole-piece I5 abuts against the disc 38. The end I5a of the polepiece I5 is riveted over the outer surface of the end wall I3, the construction being such that the end wall I3 and the disc 38 are clamped between the shoulder 39 and the riveted over portion of the end I5a. Of course, this construction also insures that the central pole-piece I6 will be secured to the pot cover I I and correctly positioned therein so that it will be disposed concentrically with respect to the aperture 34 in the outer pole-piece 35.

Interposed between the disc 38 and the outer pole-piece 35 and disposed around the central pole-piece I5 is the usual field coil 40 of the electro-magnetic structure.

It will be noted that the frustro-conical diaphragm 22 has a central integral portion 42 preferably formed integral with the diaphragm and adapted to close the outer end of the tube 3|. The periphery of the central portion 42 is secured by adhesive to the `central portion of the flexible disc 21. In the preferred form of the invention the disc 21 is not apertured and therefore co-operates with the portion 42 of the diaphragm 22 to seal the pot cover II against the entrance of dust.

It will be readily understood that the magnetic circuit comprises the central pole-piece I5a, the disc 38, the end wall I3, the cylindrical wall I2, the outer pole-piece 35 and the air gap between the outer pole-piece and the central pole-piece I5. It is in this air gap that the voice coil 33 from sheet metal and therefore it is relativelyV inexpensive. When the apparatus is to be assembled, the central pole-piece and the dis-c or Washer 38 are secured in place after'vvhich the field coil is dropped in place around the central pole-piece l5. The outer pole-piece 35 is then pressed into the position illustrated in the drawing, after which the exible disc 21 and the diaphragm 22 are secured to the structure by adhesive and by the grommets 24. assembly of the apparatus is exceedingly simple.

Secured to the frustro-conical Wall I9 of the basket 26 is an output transformer Which is designated generally by the reference character 45. The primary Winding of this transformer is generally connected to the output circuit of a radio receiving set, or the equivalent. The leads of the secondary winding may be soldered direct- Obviously, theV ly to the leads of the voice coil 33 without the use of terminal strips, eyelets, etc., or any part attached either to the transformer or tothe speaker.

While We have shown and described certain embodiments of our invention, it is to be understood that it is capable ofv many modications. Changes, therefore, in the construction and arrangement may be made Without departing from the spirit and scope ofthe invention as disclosed in the appended claim, in which it is our intention to claim all novelty inherent in our invention as broadly as permissible, in view of the prior art.

We claim:

In a sound reproducer housing, an integral, ferrous, sheet metal structure comprising a cylindrical pot portion having an apertured closure at one end, a portion of enlarged diameter adjacent its remaining end providing an interior annular shoulder, an outwardly flanged opening providing a surrounding annular shoulder-and a frusto-conical diaphragm supporting portion projecting from the outer edge of said flange.

JOHN MCWILLIAMS STONE. CARLETON T. WEIBLER. 

